JP6424336B2 - Floodlight device - Google Patents

Description

  The present disclosure relates to a light projecting device used in the field of lighting such as vehicle lighting that utilizes light generated by irradiating a wavelength conversion element with light emitted from a light source.

  Conventionally, this type of light emitting structure has a reflecting member 1041 and a light emitting member 1042 as shown in FIG. The reflecting member 1041 has a deep concave reflecting surface 1041a whose focal point is located near the vertex. The light emitting member 1042 is disposed at the focal point of the reflective surface 1041 a and its periphery, and emits light by being excited by the excitation light.

  The light emitting member 1042 is a powder obtained by mixing a powder of a fluorescent material that absorbs the excitation light L1 from the laser 1043 to generate fluorescence and is solidified with a resin or the like, or a particle of the fluorescent material is mixed with a binder and applied. .

  As prior art document information related to this application, for example, Patent Document 1 is known.

JP 2012-53995 A

  When such a conventional light projection device is used for outdoor lighting such as vehicle lighting, sunlight is incident from the outside of the light projection device, and infrared rays are condensed on the light emitting member, so that the light emitting member is deteriorated. there were.

  In order to solve the above problems, a light projecting device of the present disclosure includes a light emitting element that emits excitation light, a wavelength conversion unit that receives excitation light, converts the excitation light into light of different wavelengths, and emits the light as emitted light. And an optical filter for receiving light. The optical filter reflects long wavelength light having a wavelength longer than that of the emitted light.

  With this configuration, since the optical filter reflects long wavelength light having a longer wavelength than the emitted light, it is possible to suppress the long wavelength light from being irradiated to the wavelength conversion unit, and to suppress deterioration of the wavelength conversion unit. Can.

FIG. 1 is a schematic view of a light projecting device according to a first embodiment of the present disclosure. FIG. 2 is a diagram showing a preferable transmission spectrum of the optical filter used in the light projecting device in the first embodiment of the present disclosure. FIG. 3 is a diagram showing the spectrum of wavelength-converted light used in the light projecting device in the first embodiment of the present disclosure. FIG. 4 is a diagram showing the spectrum of sunlight incident on the light projecting device in the first embodiment of the present disclosure. FIG. 5 is a schematic view for explaining the operation of the light projecting device in the first embodiment of the present disclosure. FIG. 6 is a view showing a transmission spectrum of a specific example of the optical filter 40 used for the light projecting device. FIG. 7 is a diagram for explaining the effect of the light projecting device in the first embodiment of the present disclosure. FIG. 8 is a diagram for explaining the effect of the light projecting device in the first embodiment of the present disclosure. FIG. 9 is a schematic view of a light projecting device in a modification of the first embodiment of the present disclosure. FIG. 10 is a diagram showing a preferable transmission spectrum of the optical filter used in the light projecting device in the modification of the first embodiment of the present disclosure. FIG. 11 is a schematic view for explaining the effect of the light projecting device in the modification of the first embodiment of the present disclosure. FIG. 12A is a schematic view of a light projecting device according to a second embodiment of the present disclosure. FIG. 12B is a schematic view of the wavelength conversion unit 16 of the light projecting device according to the second embodiment of the present disclosure. FIG. 13 is a diagram showing a preferable transmission spectrum of the optical filter used in the light projecting device in the second embodiment of the present disclosure. FIG. 14 is a schematic view for explaining the operation of the light projecting device of the present disclosure. FIG. 15 is a view showing a transmission spectrum of an example of the optical filter used in the light projecting device of the present disclosure. FIG. 16 is a schematic view of a conventional light projecting device.

Embodiment 1
The light projector 1 in Embodiment 1 of this indication is demonstrated using FIGS. 1-8.

  The schematic diagram of the light projection apparatus in Embodiment 1 of this indication is shown in FIG. As shown in FIG. 1, the light projecting device 1 in the present embodiment includes a light emitting element 11, a wavelength conversion unit 16, and an optical filter 40. The light emitting element 11 emits excitation light. The wavelength converter 16 receives the excitation light, converts the excitation light into light of a different wavelength, and emits it as a wavelength converted light 76. The converted wavelength light 76 is a radiation light. The optical filter 40 receives the wavelength converted light 76. The optical filter 40 reflects long wavelength light having a wavelength longer than that of the emitted light.

  With this configuration, since the optical filter 40 reflects long wavelength light having a longer wavelength than emitted light, it is possible to suppress the irradiation of the long wavelength light to the wavelength conversion unit 16, and deterioration of the wavelength conversion unit 16 can be reduced. It can be prevented.

  Hereinafter, a more specific configuration including an optional configuration will be described.

  The light emitting element 11 is formed of, for example, a semiconductor light emitting element which is a nitride semiconductor laser having an emission center wavelength of about 405 nm and an optical output of 2 watts. In the present embodiment, three light emitting elements 11 are arranged on the heat sink 25. The light emitted from the light emitting element 11 is converted by the collimator lens 12 into the outgoing light 70 which is straight light. The light guide member 35 guides the emitted light 70 to the wavelength converter 16. The reflector 30 reflects the wavelength-converted light 76 emitted from the wavelength conversion unit 16 in the forward direction to obtain an emitted light 80 b. The reflector 30 has, for example, a metal film of Al, Ag or the like or an Al film in which a protective film is formed on the surface. The reflector 30 has a concave shape, and the wavelength conversion unit 16 is disposed inside the concave shape. The optical filter 40 is provided to cover the opening 30 a of the reflector 30.

The light guide member 35 is a component integrally molded with the support portion 16 a of the wavelength conversion portion 16, and is made of, for example, a material such as low melting glass that does not absorb light of wavelength 400 nm or more. The light guide member 35 has a conical shape whose diameter decreases toward the support portion 16a, and the support portion 16a can be integrally formed by, for example, softening the tip portion with a high-temperature furnace and forming it into a spherical shape. The phosphor layer 17 is formed to cover the support portion 16a, and specifically, for example, Eu-activated (Ba, Sr) Si ₂ O ₂ N ₂ phosphor, Ce-activated Y ₃ Al ₅ O ₁₂ phosphor, etc. And a third phosphor layer 17Y including a phosphor emitting yellow light and a phosphor emitting blue light such as Eu-activated Sr ₃ MgSi ₂ O ₈ phosphor and Eu-activated BaMgAl ₁₀ O ₁₇ phosphor. The phosphor layers 17B are sequentially formed to cover the support portion 16a. The fourth phosphor layer 17Y and the third phosphor layer 17B are mixed with a transparent material such as silicone, for example, and fixed on the support portion 16a with a mold or the like.

  In addition, the optical filter 40 preferably has a characteristic of reflecting, for example, light with a wavelength of 420 nm or less and light with a wavelength of 700 nm or more, as shown in FIG.

Subsequently, the operation of the light projecting device 1 will be described. For example, 6-watt emitted light emitted from the three light emitting elements 11 is converted into emitted light 70 which is straight light by the collimator lens 12, and is incident from the incident end 32 of the light guiding member 35 into the light guiding member 35. It will be incident. The light incident on the light guide member 35 is guided to the support portion 16 a directly or while totally reflecting the surface of the light guide member 35. A part of the emitted light 70 that has entered the support portion 16a is absorbed by the fourth phosphor layer 17Y. The light transmitted through the fourth phosphor layer 17Y enters the third phosphor layer 17B. The light incident on the fourth phosphor layer 17Y and the third phosphor layer 17B is converted to yellow light and blue light, and emitted from the wavelength conversion unit 16 as omnidirectional light as wavelength converted light 76 which is white light. Ru. The wavelength conversion light 76 emitted from the wavelength conversion unit 16 directly travels to the optical filter 40 or becomes the reflected light 80a reflected by the reflection surface of the reflector 30, and is emitted upward in FIG. At this time, as the spectrum of the wavelength-converted light 76 and the reflected light 80a is shown in Figure 3, is composed of a laser beam at a wavelength of 405 nm, a fluorescence having a peak near a wavelength 460nm and near the wavelength 570 nm, as a white light It is emitted. On the other hand, when installing such a light projection apparatus outdoors, it is necessary to take into consideration the influence of the sunlight from the sun. Sunlight has a spectrum shown in FIG. 4, and in particular, infrared rays having a wavelength of 700 nm or more are easily absorbed by the substance, which causes heat generation. In particular, in a light projecting device using the reflector 30, sunlight incident from the light projecting device is easily collected by the reflector 30 on the wavelength conversion unit 16.

  Therefore, the opening 30a of the reflector 30 is provided with an optical filter 40 having a transmittance characteristic as shown in FIG. First, since the light having a wavelength of 420 nm or less, for example, is removed when the radiation from the wavelength conversion unit 16 passes through the optical filter 40, the light 70 from the light emitting element 11 is not directly emitted. Furthermore, in sunlight incident from the outside, as shown in FIG. 5, since infrared rays are reflected by the optical filter 40, it is possible to suppress that the light is condensed on the wavelength conversion portion 16, and the wavelength conversion portion It can suppress that 16 heats up.

A specific example of the optical filter 40 is shown below. FIG. 2 shows the ideal transmission spectrum of the optical filter 40. The optical filter 40 is formed of, for example, a multilayer film of a dielectric such as MgF ₂ , SiO ₂ , Ta ₂ O ₃ , Al ₂ O ₃ , TiO ₂ or the like. The optical filter 40 according to the present embodiment reflects light with a wavelength of 420 nm or less and light with a wavelength of 700 nm or more and transmits light with a wavelength of 430 nm or more and 660 nm or less, as shown in FIG. Do.

  When the spectrum of the light emitted from the light projecting device 1 using the optical filter 40 having the transmission spectrum characteristic shown in FIG. 6 is measured under sunlight, the spectrum characteristic shown by the solid line in FIG. 7 is obtained . The spectral characteristics shown by the solid line in FIG. 7 were similar to the spectral characteristics shown by the solid line in FIG. The spectral characteristics shown by the solid line in FIG. 7 remove the influence of the reflection of sunlight in the optical filter 40. On the other hand, dotted lines in FIG. 7 indicate spectral characteristics when the optical filter 40 is not provided. The spectral characteristics shown by the dotted line in FIG. 7 are the same as the spectral characteristics shown by the solid line in FIG. From the results shown in FIG. 7, it was found that the light intensity was almost zero (no tail at the wavelength of 680 nm or more), particularly for light of 680 nm or more. That is, it was found that the sunlight does not enter the inside of the light projecting device 1 and the light does not go out of the light projecting device 1 with respect to the infrared portion of the sunlight. In addition, the emission of the laser light near the wavelength of 405 nm, which was observed when the optical filter 40 was not provided, was almost zero. Using FIG. 8, comparison is made between the emitted light emitted from the light projecting device 1 when the optical filter 40 is provided and the emitted light emitted from the light projecting device 1 when the optical filter 40 is not provided. explain. As shown in FIG. 8, the color temperature and the general color rendering index are almost the same as in the case where the optical filter 40 is not provided and in the case where the optical filter 40 is not provided. It was possible to obtain a degree of luminous flux. Specifically, while the luminous flux in the case where the optical filter 40 was not provided was 100 lm, the luminous flux in the case where the optical filter 40 was provided was 93 lm. As is apparent from these descriptions, when the light projecting device 1 of the present disclosure is used, infrared rays from sunlight can be effectively reflected without significantly changing the light emitted from the light emitting element 11.

  The optical filter 40 according to the first embodiment has characteristics of reflecting light of wavelength 420 nm or less and light of wavelength 700 nm or more, but absorbs light of wavelength 420 nm or less and light of wavelength 700 nm or more The same effect can be obtained by transmitting light having a wavelength of 430 nm or more and a wavelength of 660 nm or less.

(Modification of Embodiment 1)
Then, the modification of the light projection apparatus 1 in Embodiment 1 of this indication is demonstrated using FIG.9, FIG.10, FIG.11. In this modification, only parts different from the first embodiment will be described.

  The schematic diagram of the light projection apparatus in the modification of Embodiment 1 of this indication is shown in FIG. In the present modification, a reflector 130 is used instead of the reflector 30 of the first embodiment. The reflector 130 has an optical filter 140 formed on the inner surface of a concave concave member 31 made of a transparent material such as glass. The optical filter 140 has a concave shape, and the wavelength conversion unit 16 is disposed inside the concave shape. Preferably, as shown in FIG. 10, the optical filter 140 is made of, for example, a dielectric multilayer film, which has a property of transmitting, for example, light with a wavelength of 420 nm or less and light with a wavelength of 700 nm or more. Preferably, a transparent cover 45 made of a transparent material such as glass is disposed in the opening 30 a of the reflector 130 for protecting the wavelength converter 16 and the optical filter 40.

On the other hand, in the present modification, in the wavelength conversion unit 16, the phosphor layer 17 and the reflection member 16 b are stacked and fixed on the hemispherical support unit 16 a formed at the tip of the light guide member 35. Specifically, the fourth phosphor layer 17Y of the phosphor layer 17 may be, for example, Eu-activated (Ba, Sr) Si ₂ O ₂ N ₂ phosphor, Ce-activated Y ₃ (Al, Ga) ₅ O ₁₂ phosphor And a phosphor layer that contains a phosphor that emits yellow light. The third phosphor layer 17B is a phosphor layer including a phosphor emitting blue light such as, for example, Eu-activated (Ba, Sr) ₃ MgSi ₂ O ₈ phosphor, or Eu-activated BaMgAl ₁₀ O ₁₇ phosphor. The reflecting member 16 b is, for example, an aluminum alloy, and is disposed on the outermost surface.

Subsequently, the operation of the light projecting device 1 of the present modification will be described. The emitted light 70 emitted from the light emitting element 11 propagates through the light guide member 35 and the support portion 16a, and a part thereof is absorbed by the fourth phosphor layer 17Y. The emitted light 70 not absorbed by the fourth phosphor layer 17Y passes through the fourth phosphor layer 17Y and is incident on the third phosphor layer 17B. The light incident on the fourth phosphor layer 17Y and the third phosphor layer 17B is converted into yellow light and blue light, and is emitted from the wavelength conversion unit 16 as wavelength converted light 76 which is white light. Spectrum of this when the wavelength converted light 76, in so that shown in Figure 3, a laser beam at a wavelength of 405 nm, a white light composed of the fluorescence having a peak near a wavelength 460nm and near the wavelength 570 nm. The wavelength-converted light 76 emitted from the wavelength converter 16 travels to the optical filter 140 on the concave member 31. The light with a wavelength of 420 nm or less of the wavelength conversion light 76, that is, the component 80b of the laser light near the wavelength of 405 nm, passes through the optical filter 140, and the light converted by the wavelength conversion unit 16, ie, a wavelength of 430 nm or more and 660 nm or less The light becomes the reflected light 80a reflected by the optical filter 140, and is emitted upward in FIG.

  On the other hand, when such a light projecting device 1 is installed outdoors and sunlight is incident from the outside, infrared rays are transmitted through the optical filter 140 as shown in FIG. It can be suppressed that the light is emitted, and it is possible to suppress the heat generation of the wavelength conversion unit 16. In addition, since the reflecting member 16 b is disposed on the phosphor layer 17, it is possible to prevent the infrared ray from being directly irradiated to the phosphor layer 17 from the outside.

  As described above, in the present modification, since the optical filter 140 is a part of the reflector 130, the light projecting device 1 can be easily configured.

  In addition, although the example which has the characteristic which permeate | transmits the light of wavelength 420 nm or less and the light of wavelength 700 nm or more was shown as the optical filter 140 which concerns on the modification of the said Embodiment 1, the light of optical filter 140 is wavelength 420 nm or less The light may be absorbed at a wavelength of 700 nm or more, and the light at a wavelength of 430 nm or more and a wavelength of 660 nm or less may be reflected. Alternatively, the optical filter 140 has a characteristic of transmitting light of wavelength 420 nm or less and light of wavelength 700 nm or more, but the concave member 31 may absorb light of wavelength 420 nm or less and light of wavelength 700 nm or more. According to the above configuration, the same effect can be obtained, and it is possible to prevent infrared light and laser light from being emitted from the rear surface of the concave member 31 of the light projecting device.

Second Embodiment
Subsequently, a light projecting device and a projector according to a second embodiment of the present disclosure will be described using FIGS. 12A to 15.

  FIG. 12A is a schematic view of a configuration of a light projecting device in Embodiment 2 of the present disclosure. The same components as in the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

  The light emitting device 101 shown in FIGS. 12A and 12B has so-called red light only with a main emission wavelength of 590 nm or more and 660 nm or less and a main emission wavelength of 500 nm or more and less than 590 nm And so-called green light only, and so-called blue light only having a main emission wavelength of 430 nm or more and less than 500 nm. The light of these three colors is emitted as wavelength-converted light 76 which is continuous in time. The wavelength conversion light 76 is, for example, light having a cycle of about 8.3 ms (120 Hz), and the three primary colors are emitted in the order of blue, green and red, for example.

  The configuration of the light projecting device 101 is such that, for example, three light emitting elements 11 which are semiconductor lasers having a light output of 2 watts and a central wavelength of light emission wavelength in the range of 380 nm or more and 420 nm or less Ru. The emitted light 70 emitted from the light emitting element 11 is collected by the collimator lens 12 into the concave lens 13 and becomes straight light. The straight traveling light passes through the optical filter 14, and is condensed at a predetermined position of the wavelength conversion unit 16 by the condensing lens 15. Here, the optical filter 14 is set to transmit light with a wavelength of 380 nm or more and 420 nm or less and reflect light with a wavelength of 430 nm or more and 660 nm or less. The angle between the direction from the optical filter 14 to the wavelength conversion unit 16 and the direction from the optical filter 14 to the long wavelength absorption unit 90 is 90 degrees. Here, 90 degrees includes about 90 degrees, that is, a manufacturing error.

As shown in FIG. 12B, the wavelength conversion unit 16 has three first phosphor layers 17R, second phosphor layers 17G, and third phosphor layers 17B on the same surface on the surface of a disk-shaped metal plate. It is a configuration formed by division. The first phosphor layer 17R contains a phosphor which is, for example, Eu-activated (Sr, Ca) AlSiN. The second phosphor layer 17G contains a phosphor which is, for example, Ce-activated Y ₃ (Al, Ga) ₅ O ₁₂ . The third phosphor layer 17B contains a phosphor that is, for example, Eu-activated Sr ₃ MgSi ₂ O ₈ . In addition, the wavelength conversion part 16 of FIG. 12B is the schematic which looked the wavelength conversion part 16 in FIG. 12A from the light emitting element 11 side.

  The wavelength conversion unit 16 is configured by forming the first phosphor layer 17R, the second phosphor layer 17G, and the third phosphor layer 17B on a metal plate (supporting portion 16a) that is, for example, an aluminum alloy. There is. The first phosphor layer 17R, the second phosphor layer 17G, and the third phosphor layer 17B are formed by mixing the phosphors described above with a binder (not shown) such as dimethyl silicone, for example. The wavelength conversion unit 16 having such a configuration is rotated at a predetermined rotation speed by the rotation mechanism 20 and the rotation shaft 19. The wavelength converter 16 is rotated to prevent the emission light 70 from continuing to be irradiated to specific positions of the first phosphor layer 17R, the second phosphor layer 17G, and the third phosphor layer 17B. Can. In addition, the emission spectrum of the wavelength conversion light 76 converted by the wavelength conversion unit 16 can be set to change with time. Specifically, the emitted light 70 collected in the wavelength conversion unit 16 is converted to the wavelength converted light 76 having a main wavelength of 590 nm or more and 660 nm or less by the phosphor contained in the first phosphor layer 17R. Is converted to The emitted light 70 collected in the wavelength conversion unit 16 is converted into wavelength converted light 76 having a main wavelength of 500 nm or more and less than 590 nm by the phosphor contained in the second phosphor layer 17G. The emitted light 70 collected in the wavelength conversion unit 16 is converted into wavelength converted light 76 having a main wavelength of 430 nm or more and less than 500 nm by the phosphor contained in the third phosphor layer 17B. The central wavelength of the emitted light 70 is 380 nm or more and 420 nm or less. The converted wavelength light 76 is converted by the condensing lens 15 back into wavelength converted light, which is straight light, reflected by the optical filter 14, passes through the condensing lens 131, the light guiding element 132, and the lens 133, and exits from the light projecting device 101. It is emitted as a light 79. A long wavelength absorbing section 90 is provided on the opposite side of the condensing lens 131 as viewed from the optical filter 14.

  In the above configuration, the transmittance characteristics of the optical filter 14 preferably transmit, for example, light with a wavelength of 420 nm or less and light with a wavelength of 700 nm or more and light with a wavelength of 430 nm or more and 660 nm or less as shown in FIG. It has the characteristic of reflecting.

  Even when sunlight or the like enters the light projecting device 101 from the outside by this configuration, most of the infrared rays 81 pass through the optical filter 14 and are absorbed by the long wavelength absorbing portion 90 as shown in FIG. . Therefore, it can suppress that sunlight etc. injects into the wavelength conversion part 16, and condenses, and it can suppress that the wavelength conversion part 16 degrades.

A specific example of the optical filter 14 is shown below. FIG. 13 shows the ideal spectral characteristics of the optical filter 14. The optical filter 14 is composed of, for example, a multilayer film of SiO ₂ and TiO ₂ . The optical filter 14 in the present embodiment transmits light with a wavelength of 420 nm or less and light with a wavelength of 730 nm or more and has a wavelength of 430 nm or more and 660 nm or less, as shown in FIG. reflect.

  When the spectrum of the radiation light emitted from the light projector 101 under sunlight is measured using the optical filter 40 having the transmission spectrum characteristic shown in FIG. 15, the spectrum comparison shown using FIG. 7 of the first embodiment Similar results were obtained. That is, there was almost no difference in color temperature and general color rendering index between the case where the optical filter 40 was used and the case where it was not used. As is clear from these descriptions, when the light projecting device 101 of the present disclosure is used, infrared rays from sunlight can be effectively reflected without significantly changing the light emitted from the light emitting element 11.

In addition, Eu-activated Sr ₃ MgSi ₂ O ₈ phosphor and Eu-activated BaMgAl as phosphors for blue light, green light, yellow light and red light used for the light projecting device shown in the first and second embodiments. ₁₀ O ₁₇ phosphor, Ce activated Y ₃ (Al, Ga) ₅ O ₁₂ phosphor, Eu activated (Ba, Sr) Si ₂ O ₂ N ₂ phosphor, Ce activated Y ₃ Al ₅ O ₁₂ , Eu activated (Sr activated) , Ca) AlSiN etc. are shown but not limited to this. For example, in addition to the phosphors described above, for example, Eu-activated CaAlSiN, Ce-activated Y ₃ Al ₅ O ₁₂ phosphor, Eu-activated β-SiAlON, Eu-activated α-SiAlON, Eu-activated (Sr, Ca, Ba) ₃ MgSi ₂ O ₈ , Eu activated (Sr, Ca) ₃ MgSi ₂ O ₈ , Eu activated (Sr, Ba) ₃ MgSi ₂ O ₈ , Eu activated (Sr, Ca, Ba) ₂ MgSi ₂ O ₇ , Eu activated (Sr , Ca) ₂ MgSi ₂ O ₇ , Eu activated (Sr, Ba) ₂ MgSi ₂ O ₇ or the like may be optimized.

  The light projection device of the present disclosure is useful in a lighting device used outdoors such as a vehicle light, and has an effect that the durability can be improved.

Reference numeral 1, 101 Light emitting device 11 Light emitting element 12 Collimator lens 14, 40, 140 Optical filter 16 Wavelength converter 16a Supporter 17 Phosphor layer 17R First phosphor layer 17G Second phosphor layer 17B Third phosphor Layer 17Y Fourth phosphor layer 25 Heat sink 30, 130 Reflector 30a Opening 31 Concave member 32 Incident end 35 Light guiding member 70, 79, 80b Emitted light 76 Wavelength converted light 80a Reflected light 81 Infrared 90 Long wavelength absorbing portion

Claims (7)

A light emitting element that emits excitation light;
A wavelength conversion unit that receives the excitation light, converts the excitation light into light of different wavelengths, and emits the light as emitted light;
An optical filter for receiving the radiation light ;
The optical filter has a concave shape,
The wavelength converter is disposed inside the concave shape;
The optical filter transmits the excitation light and infrared light, and reflects the emitted light.   The light projecting device according to claim 1, wherein the optical filter reflects light having a wavelength of 430 nm or more and 660 nm or less. The optical filter is formed on the inner surface of a concave member,
The concave member, the light projection device according to claim 1 or 2, characterized in that to absorb the light transmitted through the optical filter. The light projecting device according to claim 3, wherein the concave member absorbs light having a wavelength of 420 nm or less and light having a wavelength of 700 nm or more . A light emitting element that emits excitation light;
A wavelength conversion unit that receives the excitation light, converts the excitation light into light of different wavelengths, and emits the light as emitted light;
An optical filter that receives the radiation;
And a long wavelength absorbing section for receiving long wavelength light having a wavelength longer than that of the radiation light,
The optical filter transmits the long wavelength light,
The projector according to claim 1, wherein the long wavelength light is absorbed by the long wavelength absorbing portion . The light projecting device according to claim 5, wherein an angle between a direction from the optical filter to the wavelength conversion unit and a direction from the optical filter to the long wavelength absorbing unit is 90 degrees . 7. The light projecting device according to claim 5, wherein the long wavelength light is light in an infrared wavelength band .

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